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From: stanley@west.sun.com (Stanley Friesen [Contractor])
Subject: Re: nested functions
Date: 1999/06/09
Message-ID: <7jma5c$i85@abyss.West.Sun.COM>#1/1
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In article <7jjjr6$r02$1@nnrp1.deja.com>,  <wmm@fastdial.net> wrote:
>In article <7jd4c5$nup$1@nnrp1.deja.com>,
>1) Runtime overhead.  The function calling sequence has to be
>modified to maintain a display pointer or the like. ...

Why do local functions have to have the same calling sequence as non-local
functions?  Given the C++ requirement for all functions to be declared
prior to a call, the compiler can always tell if a call is to a namespace
scope funcion or to a local one.
>
>2) Implementation complexity.  Although the problems are well
>understood from experience with other languages, people felt that
>the utility of nested functions was sufficiently limited that it was
>not a good tradeoff.

2.5) The potential for writing obscure code due to "hidden" references
to mid-scope variables is not worth the small gain in utility.

[One of the hardest to maintain programs I ever saw was an assembler
written in Pascal that made heavy use of local functions, and of the local
function's ability to access variables in containing functions].
>
>3) C data compatibility.  A function pointer in C is a simple object,
>just the address of the code of the function.  A pointer to a nested
>function is more complex, requiring a pointer to the automatic
>storage area.  ...

Since pointer-to-member-functions are already non-compatible with ordinary
function pointers, why do pointers to local functions need to be compatible
either?  Why not just use a different category of pointers for pointers
to local functions?


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